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Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Futakawa, Masatoshi
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 8 Pages, 2010/07
In the J-PARC, the cryogenic hydrogen system for the 1MW pulsed spallation neutron source (JSNS) plays a role in supplying supercritical hydrogen at a temperature of 18 K and pressure of 1.5 MPa to three moderators in which spallation neutrons generated in a mercury target are slowed down to cold neutrons. Through the off-beam commissioning until April 2008, we confirmed that the specifications of the cryogenic system were satisfied as expected, and we could succeed in circulating supercritical hydrogen with the maximum flow rate of about 190 g/s. We have succeeded in generating first neutrons in the mercury target and providing moderated neutrons through the hydrogen moderators without any problems in May 2008. We also confirmed characteristics of the cryogenic hydrogen system with accepting the proton beam on the mercury target as on-beam commissioning.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi
Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.1009 - 1014, 2010/07
The cryogenic hydrogen system provides supercritical hydrogen to three hydrogen moderators and removes the nuclear heating of 3.75 kW for a 1-MW proton beam operation at the J-PARC. A pressure control system that used a heater and an accumulator was designed to mitigate a pressure fluctuation caused by the sudden heat load of kW-order. The temperature and pressure behaviors were studied for a 300-kW beam operation. It was confirmed that the pressure control system made it possible to reduce the pressure fluctuation below 13.5 kPa. A simulation model was derived and could describe the experimental results within 15% errors.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi; Yoshinaga, Seiichiro*
Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.377 - 382, 2010/07
A dynamic gas bearing centrifugal pump that circulated supercritical hydrogen with a large flow rate of more than 0.16 kg/s was developed to minimize the hydrogen density change at the moderator. The two pumps were simultaneously operated in parallel for redundancy. The performance test results indicated that the dimensionless characteristics for the single and the parallel operations existed on an identical curve. An outstanding peak adiabatic efficiency exited at the flow coefficient of 0.046, independently of the revolution. It was verified that the developed hydrogen pump satisfied the design requirement.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi
Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.601 - 606, 2010/07
At the J-PARC, the cryogenic hydrogen system provides supercritical hydrogen to three hydrogen moderators and removes the nuclear heating evolved by converting high energy neutrons into cold neutrons. As safety countermeasure, fail-safe devices such as relief valves and rupture disks are installed and a hydrogen explosion-proof structure is adopted. Additionally, the safety interlock system that is divided into 7 categories based on the trouble events is established to protect the equipments and to ensure the safety at the occurrence of a trouble. It is confirmed that the interlock system can be operated without any problems. The recovery procedures are also established.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi
AIP Conference Proceedings 1218, p.297 - 304, 2010/04
Times Cited Count：2 Percentile：74.08In JSNS, supercritical hydrogen at around 20 K and 1.5 MPa was selected as a moderator material. Three kinds of hydrogen moderators are installed to provide pulsed neutron beam with higher neutronic performance. A cryogenic hydrogen system, in which a hydrogen circulation system is cooled by a helium refrigerator system with the refrigerator capacity of 6.45 kW at 15.6 K, provides the supercritical hydrogen to the moderators and absorbs nuclear heating in the moderators. Through the off-beam commissioning, we have confirmed that the cryogenic hydrogen system can be cooled down to 18 K within 19 hours. The supercritical hydrogen with the mass flow rate of 190 g/s can be circulated at the rated condition. It is verified that the cryogenic hydrogen system is satisfied with the performance requirements. In May 2008, we have succeeded in providing the first cold neutron beam cooled by the cryogenic hydrogen system.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Hasegawa, Shoichi; Futakawa, Masatoshi
AIP Conference Proceedings 1218, p.289 - 296, 2010/04
Times Cited Count：2 Percentile：74.08A cryogenic hydrogen system provides the supercritical hydrogen to the moderators and removes the nuclear heating at the moderators, which is estimated to 3.8 kW for a proton beam power of 1 MW. In order to mitigate pressure fluctuation caused by suddenly turning a proton beam on and off, we should design a pressure control system, which is composed of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller. In December 2007, a 109 kW proton beam was injected to the JSNS. The pressure fluctuation behaviors have been studied for the 109 kW proton beam operation. As soon as the proton beam is injected, the accumulator starts to spontaneously constrict. The heater control can succeed in maintaining a constant heat load applied to the cryogenic hydrogen system. The pressure control system can reduce the pressure fluctuation below 5 kPa. We have confirmed that the pressure control system should be effective.
Aso, Tomokazu; Tatsumoto, Hideki; Hasegawa, Shoichi; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Maekawa, Fujio; Futakawa, Masatoshi; Ushijima, Isamu*
Proceedings of International Cryogenic Engineering Conference 22 (ICEC-22) and International Cryogenic Materials Conference 20 (ICMC 2008), p.741 - 746, 2009/00
no abstracts in English
Hasegawa, Shoichi; Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko*; Sakurayama, Hisashi; Kato, Takashi
no journal, ,
In JSNS, supercritical hydrogen is adopted as a moderator material. A heat load of moderators is changed by fluctuation of nuclear heating due to pulsed proton beam. The maximum nuclear heating is estimated to be 3750W at 1MW proton beam. Therefore, a pressure control system should be required for the hydrogen system. A hybrid pressure control system, which consists of a heater and an accumulator, is prepared. The heater compensates a heat load of the nuclear heating, and the accumulator has a variable volume to absorb pressure fluctuation. The design of hybrid pressure control system required the estimation of hydrogen pressure behaves. An original computer code was developed to analyze such pressure behaviors in the various cases of nuclear heating change, for example proton beam on and off. Then the analysis result determined the capacity of the accumulator and the analysis indicated that the pressure change could be controlled within 0.15MPa by the designed hybrid control system.
Aso, Tomokazu; Tatsumoto, Hideki; Hasegawa, Shoichi; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko*; Sakurayama, Hisashi; Maekawa, Fujio; Kato, Takashi
no journal, ,
no abstracts in English
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kato, Takashi; Hasegawa, Shoichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko
no journal, ,
no abstracts in English
Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Futakawa, Masatoshi; Ushijima, Isamu*; Yoshinaga, Seiichiro*
no journal, ,
A centrifugal hydrogen pump that is a foil type self acting gas bearing had developed for the cryogenic hydrogen system in J-PARC, and the performance test was carried out in the system operation. The cryogenic hydrogen system plays a role in supplying supercritical hydrogen at a temperature of around 20 K and pressure of 1.5 MPa to three moderators and removing the nuclear heating of 3.8 kW at a proton beam of 1 MW from accelerators. In order to satisfy the neutronic performance, the temperature difference through the moderator should be reduced below 3 K. Therefore, cryogenic supercritical hydrogen should be circulated with the mass flow rate more than 160 g/s. We confirmed the characteristics of the pump satisfy the required performance.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Hasegawa, Shoichi; Sakurayama, Hisashi; Kawakami, Yoshihiko; Uehara, Toshiaki; Kato, Takashi
no journal, ,
no abstracts in English
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Hasegawa, Shoichi
no journal, ,
no abstracts in English
